$WsusServer = "localhost"
$UseSSL = $false
$PortNumber = 8530

#Connect to the WSUS interface.
[reflection.assembly]::LoadWithPartialName("Microsoft.UpdateServices.Administration") | out-null
$WsusServerAdminProxy = [Microsoft.UpdateServices.Administration.AdminProxy]::GetUpdateServer($WsusServer,$UseSSL,$PortNumber);

#Create Object for WSUS Server
$CleanUpScope = New-Object Microsoft.UpdateServices.Administration.CleanupScope

#Define Scope for cleanup by setting on true / false
$CleanUpScope.CleanupObsoleteUpdates = $true
$cleanUpScope.CleanupObsoleteComputers = $true
$cleanUpScope.CleanupUnneededContentFiles = $true
$cleanUpScope.DeclineExpiredUpdates = $true
$cleanUpScope.DeclineSupersededUpdates = $false
$cleanUpScope.CompressUpdates = $true

#create object for cleanup manager
$cleanUpManager = $WsusServerAdminProxy.GetCleanupManager()

#trigger cleanup
$CleanUpManager.PerformCleanup($cleanupScope)